A folded piece of paper fell out of Scott Rolen's pocket as he pulled on his pants after delivering one of his most important hits of the season.

"It's a paycheck,'' Rolen said, scooping up the paper. "They handed me this when I came in. What a good day!''

For the Reds, that was an understatement.

Rolen's tiebreaking bases-loaded single in the eighth inning set up a 4-2 victory and three-game sweep of the St. Louis Cardinals on Sunday night, leaving Cincinnati alone in first place in the NL Central.

The Reds' sixth straight win matched their longest streak of the season, moved them a season-high 12 games over .500, and bumped them a game ahead of Pittsburgh for the division lead. St. Louis fell 4 1/2 games back.

Rolen's two-out single off Mitchell Boggs snapped a 2-all tie and provided a satisfying moment for the 37-year-old third baseman, limited all season by a bad shoulder and back. He's had trouble getting in the lineup lately because of back spasms.

Against the hard-throwing Boggs, Rolen took a scaled-back approach, lining the ball to the opposite field.

"I was just trying to get a good pitch and put a good swing on it,'' Rolen said. "I haven't been doing a lot of that lately.''

It was the second straight day that a former Cardinal beat St. Louis. Ryan Ludwick hit a game-ending homer in the 10th for a 3-2 win on Saturday night.

Jake Westbrook (7-8) set up the winning rally with a walk, a wild pitch and a hit batter. He walked Joey Votto with one out, threw a wild pitch and hit Brandon Phillips on the arm, ending his outing.

"I hadn't walked a guy all night, and I walked him,'' Westbrook said. "Then I hit Phillips, which ultimately cost us the game.''

Homer Bailey (8-6) went eight innings during a fill-in start for Johnny Cueto, sidelined by a blister. Bailey gave up two runs -- one earned -- and nine hits while winning his third straight start.